The present disclosure relates to the fabrication of a semiconductor device, and in one embodiment to a method of fabricating a metal oxide semiconductor field effect transistor (MOSFET) having a retrograded well.
Over the past twenty-five years or so, the primary challenge of very large scale integration (VLSI) has been the integration of an ever-increasing number of MOSFET devices with high yield and reliability. This was achieved mainly by scaling down MOSFET channel lengths without excessive short-channel effects. Short-channel effects are the decrease in threshold voltage (Vt) in short-channel devices due to two-dimensional electrostatic charge sharing between the gate and the source/drain regions.